I run the mono version of Smath Studio on KDE Linux. I attempted to update version 0.99.7822 but all more recent mono versions will not launch from the desktop file (but I can run them from the terminal line using 'sudo mono SMathStudio_Desktop.exe'.) My desktop file is set to run SMathStudio_Desktop.exe as root; this works fine for version 0.99.7822.

Also, it appears that recent versions require a version of .NETFramework that Mono does not provide.
So far, the 2021-era version is sufficient for me; I just wanted to register these problems. And thanks! I am keeping calm and calculating.

Wrote

I run the mono version of Smath Studio on KDE Linux.

I take you are using KDE Neon, which is debian based.
Debian based distros have a mono bug, caused by glibc.
Not only SMath, some mono programs don't work also without sudo.
So far only debian or ubuntu based distro I could
make all mono programs run without sudo is MXLinux (ahs).
It has a linux kernel v6+ and an updated glibc also.
Maybe this is the reason why it works and LTS versions are not.
I will download your OS and check in a VM if this is the reason.

And for desktop file issue, file/script below is what I use.
I use a dark theme but SMath doesn't look good with it.
Script also change theme to a light one just for SMath.

Regards

smathstudio_desktop_mono.tar.gz (285 B) downloaded 63 time(s).

I tried SMath official appimage with latest stable KDE Neon under Qemu.
It worked flawlessly. No issues with starting, installing plugins, etc.

SMathStudioDesktop.1_0_8348.x86_64.ubuntu-22_04.glibc2.35.AppImage

Regards